A wide variety of processes are known for forming dough intermediates into final products. Examples of such products include tortillas, pizza crusts, pie crusts, pastries, and cookies as well as snack products, including chips or crisps and fruit snacks.
It is widely recognized that many aspects of the manufacturing processes can have a substantial impact on the price that a consumer pays for the product. Usually, the cost of a product decreases in proportion to an increase in the speed with which the product can be fabricated. Additionally, process improvements that simplify the associated equipment may lead to decreases in the costs of obtaining and operating such equipment.
In the manufacture of flat products such as tortillas, piecrusts, snack products, and the like efforts have been increasingly directed toward reducing costs and increasing the speed of production. Traditionally, several manufacturing techniques have been utilized for economically and quickly forming tortillas on commercial production lines. A first popular method is known as die-cutting and a second popular method is known as pressing, both of which are described below.
In the die-cutting technique, tortilla dough is first formed in a commercial mixer. The dough is then transferred to an extruder that extrudes a sheet of dough onto a conveyor belt of a rolling and cutting machine to form a dough ribbon. In this step, the dough ribbon is gradually reduced to a predetermined thickness by sheeting and cross-rolling.
Once the dough has reached a desired thickness, a die is actuated to cut the dough into the desired form. The formed dough products are then separated from the remaining matrix and are moved to an oven where they are cooked. The matrix is usually returned to the extruder for reprocessing.
Several problems and limitations exist with the die-cutting method described above. One such problem is that the remaining matrix is often coated with flour prior to cutting to prevent the die from sticking to the dough. When this dough and flour is reprocessed, the extra flour and floor time can produce undesirable properties within the dough. For example, the flour can inhibit re-mixing, causing the subsequently processed dough product (e.g. tortilla) to be substantially inflexible or brittle, and may produce an undesirable taste in the product.
In addition, having the dough products produced by this method usually has a rheoligical bias in the direction of sheeting. That is, the tortilla will crack when folded in the direction that is transverse or perpendicular to the direction of the sheeting. Moreover, the sheeting process described above does nothing to seal the surface of the dough. Sealing the surface of the dough traps leavening gasses during baking which has been found to improve final bake quality of the product.
As mentioned above, a second common process for forming tortillas is by pressing, which is also referred to as the hot press method. In practice, dough balls are formed, proofed, and fed onto a conveyor that carries several dough balls at a time into position between the heated platens (up to 450° F.) of a tortilla press. Such relatively high temperatures must be imparted to the tortillas by the platens to overcome the inherent elastic tendency of the dough to snap-back after pressing. In other words, without sufficiently heating the dough, the tortillas will typically thicken and shrink in size, snap back or return to its original size. In addition, dough properties can vary from batch to batch, and may also vary significantly within a single batch. This creates further problems in providing a consistent and uniform product from a consumer standpoint.
In the pressing process, a batch of dough balls are positioned between heated press platens, the conveyor is then stopped and the press is closed compressing the balls into circularly shaped tortillas that are then transferred into an oven for baking. Using this method, the tortillas may be formed at reasonable production speeds, however, the time required for opening and closing the press and indexing the belt carrying the dough severely limits production to about 14 to 16 strokes per minute.
In addition, to limited production speeds, this method suffers from other drawbacks. For example, the individual components are more expensive when compared with a die cutting operation. Moreover, the intermittent movement and engagement of the platens adds further complexity to the system. Additionally, alignment of the dough balls with the press platens increases the difficulty in operating the equipment and may contribute to other problems, such as, misalignment which can lead to the tortillas being irregular or have a non-uniform thickness, such that they are not of an acceptable quality.
What is needed therefore, is an apparatus that overcomes the difficulties set forth above and which can process flat dough products in an efficient manner while maintaining consistently good, quality products.